The present invention pertains to brushless servo drive systems, and more particularly, to a current and torque feedback system and circuitry for use with sine-wave controlled brushless servo motors.
A brushless servo motor can be defined as a motor which includes a stator having a plurality of fixed windings; a rotor having permanent magnets attached to the rotor; and a means of sensing rotor position. A servo amplifier coupled to the stator windings and to the rotor sensor provides current to the stator windings to control rotation of the servo motor. The amount of torque developed by the servo motor is determined by the strength of the magnetic field produced by the rotor magnets, by the length of the wire of the windings in the magnetic field and by the amount of current in the windings. The servo amplifier controls the amount of current to the stator windings to control motor torque; and the servo amplifier also controls the speed of rotation of the motor.